深藏不露

An office worker named Dorine is called upon to do late work; her computer breaks down and she asks the help of a co-worker, Gary Michaels, who is electrocuted while trying to fix the wires. Dorine dials 911, but hangs up when the call is answered. She places the corpse on a cart, rolls it down to her car, loads it in her trunk, and takes it home, placing it in her furnished basement (we don't see the body until later). Then, seemingly without reason, she goes into a murder spree. She kills Virginia[who?] by poisoning her inhaler tube, taking the second corpse to her basement, placing it on a sofa, next to Gary's. Then comes the turn of two young Girl Scouts who arrive at her door to sell cookies. The young girls join the other corpses in the basement, Dorine seen eating the cookies with relish while working on her new laptop. Intriguingly, she sends messages from Gary to the remaining office workers, implying he is alive and has left the office or his wife. There are three more murders before the movie ends, all planned with cool design and seeming absence of malice. The last scene shows Dorine, after her mother's death, setting fire to her basement, then, sporting a blond wig, driving away in her car, circling a newspaper ad with her pencil for an office job, a look of triumph in her face.(From Wikipedia)